1. Field of the Invention
This invention generally relates to a clutch cover assembly. More specifically, the present invention relates to a clutch cover assembly, which has a wear compensation mechanism to compensate for the wear occurring in the friction members to maintain the initial pressing load.
2. Background Information
A clutch cover assembly of a clutch device is installed on a flywheel of an engine and transmits driving power of the engine to the transmission by biasing friction facings of the clutch disk assembly toward the flywheel with spring force of a diaphragm spring. In this type of clutch device, once wear of the friction facings exceeds a certain amount, the friction facings become unusable or the diaphragm spring of the clutch cover changes the angle, changing the pressing load applied by the diaphragm spring. As a result, a clutch disk assembly needs to be replaced. It is desirable to produce a clutch device that delays the replacement time for the clutch disk assembly. In other words, it is desirable to extend the life of a clutch.
To extend the life of a clutch, it is important to increase the effective thickness of friction facings of a clutch disk assembly. Therefore, friction facings are often fixedly coupled to a cushioning plate without using a rivet.
In a clutch cover assembly, when the friction facings are worn, the angle of a diaphragm spring needs to be changed back to the initial state. To accomplish this adjustment, the wear amount of the friction facings is measured and a supporting member (a fulcrum ring on the pressure plate side or a supporting mechanism on the clutch cover side) of the diaphragm spring is moved by a distance corresponding to the measured wear amount. This way, the friction facings of the clutch disk assembly can be fully utilized.
An example of a prior art clutch cover assembly, which has a wear compensation mechanism, is disclosed in the Japanese Patent Publication 6-42553. The wear compensation mechanism that is disclosed in the Japanese Patent Publication 6-42553 mainly comprises a fulcrum ring, a biasing mechanism and a regulating mechanism. The fulcrum ring is disposed between a clutch cover and a diaphragm spring. The biasing mechanism is positioned to bias the fulcrum ring away from a pressure plate. The regulating mechanism is designed to keep the fulcrum ring from moving away from the pressure plate and allow the fulcrum ring to move in the axial direction relative to the pressure plate by the wear amount when the friction facings wear.
The regulating mechanism, shown in the FIG. 3 of the Japanese Patent Publication 6-42553, includes a pair of wedge members and a spring. The wedge members are disposed between the pressure plate and the fulcrum ring, while the spring biases both of the tilted surfaces of the wedge members relative to each other in a circumferential direction. The first wedge member is fixedly coupled to the fulcrum ring. The second wedge member is disposed in a groove of the pressure plate and is movable in a circumferential direction. The spring is disposed between the first wedge member and the second wedge member and is compressed in the circumferential direction. As a result, the spring presses the first wedge member and the second wedge member in the circumferential direction biasing the tilted surfaces of the first wedge member and the second wedge member relative to each other in the circumferential direction. In this way, the second wedge member and the fulcrum ring are constantly biased in a direction to move away from the pressure plate. As the regulating mechanism allows the fulcrum ring to move, the second wedge member moves in the circumferential direction, thereby moving the first wedge member in the axial direction. As a result, the fulcrum ring is separated from the pressure plate by the wear amount of the friction facings, and the angle of the diaphragm spring returns to the initial state.
A biasing mechanism in a conventional wear compensation mechanism as described above has a spring disposed between a pressure plate and a fulcrum ring. Therefore, the space provided for accommodating a supporting structure for the spring is limited. Also, because of the spring, not much space is left for enough number or space of attaching surfaces of wedge members.
In view of the above, there exists a need for a clutch cover assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.